1. Field of the Invention
The present invention relates to a secondary battery, and in particular, to a case for a secondary battery.
2. Description of Related Art
Secondary batteries, classified into low-capacity batteries and high-capacity batteries, are distinguished from the primary batteries in that secondary batteries are rechargeable. The low-capacity batteries are used as the power source for small portable electronic devices, such as cellular phones, laptop computers, and camcorders, whereas the high-capacity batteries are used as the power source for driving motors in hybrid electric vehicles and the like.
A secondary battery may be formed with various shapes, such as a cylindrical shape and a prismatic shape. In order to drive a motor for the electric vehicle requiring high electrical power, a plurality of high capacity secondary batteries are connected to each other to thereby form a battery module.
Because a battery module is constructed by interconnecting multiple secondary batteries, the heat generated at the respective secondary batteries should be dissipated well. Particularly when a battery module is used to drive a motor for an electronic washer, an electric scooter or a vehicle (an electric vehicle or a hybrid electric vehicle), it is important to have adequate heat dissipation.
If heat is not dissipated properly, the heat generated from secondary batteries causes overall temperature elevation of the battery module, and as a result, any equipment with the battery module may suffer device failure.
Particularly, as in the case of a battery module for a vehicle, the battery is charged and discharged by a high electric current, and the heat generated due to the internal reaction of the secondary batteries during usage may be elevated to a considerable degree. This severely affects the intrinsic characteristics of the batteries, and deteriorates their inherent capacity.
As the internal pressure of a secondary battery is increased due to the internal chemical reaction thereof, the shape of the battery may become skewed so as to affect the intrinsic characteristics thereof. The problem may be heightened particularly when the ratio of the width of the battery to the length becomes similar to that of a prismatic-shaped secondary battery.
Accordingly, conventional battery modules have a barrier wall disposed between neighboring secondary batteries to support the batteries and to create a gap for ventilating cool air. In this way, the secondary batteries are cooled, and their structural distortion is prevented.
However, with the addition of the barrier walls the secondary battery module has an enlarged volume which is not desirable since the battery module is installed within a confined area. Moreover, more processing steps are needed to form the barrier walls resulting in increased production cost and lowered price competitiveness.